Electromagnetic latching relay



1963 E. R. CALLENDER ELECTROMAGNETIC LATCHING RELAY Filed Sept. '7, 1966 fzzsalatz'aa. w

United States Patent 3,396,351 ELECTROMAGNETIC LATCHING RELAY Earl R. Callender, Pittsburgh, Pa., assignor to Westinghouse Air Brake Company, Swissvale, Pa., a corporation of Pennsylvania Filed Sept. 7, 1966, Ser. No. 577,699 17 Claims. (Cl. 335-113) ABSTRACT OF THE DISCLOSURE An electromagnetic relay including a pivotal bell-crank latch and an electromagnetic release. One arm of the bellcrank is used to lock the movable armature of the relay in a predetermined position and the other arm of the bell-crank cooperates with the movable member of the electromagnetic release to permit unlocking of the movable armature.

that excessive electrical power need not be consumed in continually energizing and holding the relay in its pickedup position. While numerous types of latching arrangements have been previously proposed, it is noted that these previous proposals normally lacked certain essential characteristics and necessary requirements which generally limited their use to a substantially ideal milieu. Since many relays have universal application, it is understand able that a latching mechanism .or device for use in such relays to be economically justifiable in terms of reliability versus cost, it too must be capable of such wide-spread usage. That is, a latching device which limits the general usage of a relay is completely intolerable and unacceptable in that the integrity of the basic relay is totally destroyed. Accordingly, in order to be wholly acceptable, a latching device must be as reliable as the relay itself under all .operational conditions. For example, many of these former latching relays were susceptible to false and erratic operations due to premature unlatching normally caused by severe shock and extreme vibrations. It has been found that this problem is quite prominent in railroad applications where in many instances the relays are mounted on Diesel-electric locomotives or mounted in instrument cases along the railroad right-of-way and as a consequence these relays are subjected to continuous or repeated agitation. Hence, it is essential and of the utmost importance that in railroad applications a latching mechanism must positively lock and hold the relay in its given position even when exposed to severe shock and extreme vibrations.

In addition to the qualities of maintaining the integrity and reliability of a relay, it is advantageous that the latching mechanism be simple in design, inexpensive to manufacture, easy to install and replace, free .of abrasiveness, facile to adjust and possessed of longevity.

Accordingly, it is an object of this invention to provide a new and improved latching mechanism having all of the above-mentioned advantageous features.

A further object of my invention is to provide a unique relay latching mechanism which is not adversely affected by extreme shock or vibrations and which, therefore, does not limit the usage of the basic relay.

A still further object of my invention is to provide an electromagnetic relay with an improved latching arrangement which retains the integrity .of the relays universal usage.

Patented Aug. 6, 1968 A still further object of my invention is to provide an electromagnetic relay with a mechanical latching means and an electromagnetic releasing means which are in intimate contact with each other only during the unlatching of the relay.

Yet another object of my invention is to provide an electromagnetic relay having a mechanical latch and an electromagnetic release which are normally out of contact with each other.

Still yet another object of my invention is to provide an integral mechanical latch as well as an integral electromagnetic release which may be quickly and easily installed and replaced.

Still yet a further object of my invention is to provide a small, inexpensive, reliable, simple, shock-proof, longlived, easily maintained and serviced latching mechanism which retains the integrity and security .of the basic electromagnetic relay.

Other objects and further advantages of my invention will become apparent to those skilled in the art as the description proceeds.

In brief, the objects of my invention are achieved by providing a latching mechanism comprising an integral mechanical latch unit for automatically locking and holding an electromagnetic relay in its operated position, and an integral electromagnetic release unit which is normally out of engagement with the mechanical latch, but which is eifective upon actuation to engage the mechanical latch for unlatching and permitting the electromagnetic relay to return to its unoperated position. More specifically, my latching mechanism has been specifically designed and adapted for use in an electromagnetic relay of the type shown in the United States Patent No. 2,897,317, issued July 28, 1959, to Andrew Hufnagel, for Electromagnetic Switching Devices, which is assigned to the assignee of my present application. In actual practice, the integral mechanical latch consists of a bracket member having a pair of upstanding arms for pivotally supporting a lever about an axis which is oiiset below and parallel with the longitudinal axis of the electromagnet relay. The lever is in the form of a bell-crank having the free end of one arm provided with a hook-like portion which cooperates with an extending tab portion of the armature of the electromagnetic relay. The other end of the bell-crank lever is horizontally disposed in normal relationship with the longitudinal axis of the electromagnetic relay. A generally L-shaped leaf spring constantly urges the hook-like portion toward the portion of the relay armature tab. The electromagnetic release includes a core, coil and armature which is identical to that of the electromagnetic relay. The electromagnetic release is disposed beneath and in parallel relationship with the electromagnetic relay. The extending tab portion of the electromagnetic release armature is in spaced relationship with the horizontally disposed arm of the lever and normally out of engagement therewith. In this case, the armature of the electromagnetic release is normally biased by gravity against an upwardly projecting stop member which extends from the bracket member for maintaining the proper air gap. Upon energization of the electromagnetic relay, its armature moves downwardly which in turn permits the hook-like portion to engage the upper surface of the armature tab portion for locking and holding the relay in its picked-up position. This positively locks and holds the relay in its operated position so that the relay operating coil may be immediately deenergized. In order to restore the electromagnetic relay to its released position, it is simply necessary to energize the coil of the electromagnetic release so that its extending tab portion moves into engagement with the horizontal arm of the bell-crank lever as the armature of the electromagnetic release is pulled upwardly toward its core. The movement of the release armature overcomes the force exerted by the L-shaped leaf spring causing rotation of the bell-crank lever and disengagement of the hook-like portion with the tab portion of the electromagnetic relays. This allows the restoring springs to return the electromagnetic relay to its released position.

I shall describe one form of an electromagnetic latching relay arrangement embodying my invention and will then point out the novel features thereof in the appended claims.

My invention will be better understood after a consideration of the following detailed description and with reference to the accompanying drawings wherein:

FIG. 1 is a side elevational view, partly in section, showing my novel latching mechanism applied to a conventional electromagnetic relay.

FIG. 2 is an enlarged partial sectional view of the assembly in the unlatched condition shown in FIG. 1 taken substantially along line II-II of FIG. 1.

FIG. 3 is a partial sectional view taken substantially along line III- H1 of FIG. 2.

.FIG. 4 is a partial sectional view of the latching mechanism in its latched condition.

Referring now to the drawings, and in particular to FIG. 1, I have shown a conventional multicontact relay, generally characterized by numeral 1, which may be of the type shown and described in United States Patent No. 2,897,317, mentioned above. As described in the above, patent, the relay generally comprises an energizing coil 2 mounted on the center leg of an E-shaped rectangular core 3 which is secured at one end to the base of a molded block of insulating material 4. Pivotally mounted to cooperate with the upper face 5 of the core 3 is a U-shaped armature 6 which extends rearwardly along the outer lengths of the core 3 on either side of coil 2 in such a position that the bight of the U will cooperate with the forwardmost end of the core face 5 in the energized condition of coil 2. The free end or bight portion of the armature 6 is provided with a tongue or tab portion 7, the function of which will be described in greater detail hereinafter.

A contact stack, comprising a plurality of contact springs 8 and 9 is mounted in insulative spaced relationship on insulative block 4. The movable contact springs 8 and the fixed contact springs 9 extend forwardly of the block 4 in approximate parallelism and have contact tip points 10 and 11, respectively, at the forwardmost ends of the contact springs so that upon any contact closure the points on the cooperating fixed and movable springs are brought into engagement. The action of the movable springs 8 is controlled by a movable or operating ladder 12 of insulating material provided with projecting shoulders (shown in greater detail in FIGS. 2 and of the above-mentioned United States Patent No. 2,897,317) which engage the contact springs 8 during the various conditions of coil 2. For example, the ladder shoulders will engage front contact springs 8 (the upper and lower one in FIG. 1) when coil 2 is deenergized and back contact spring 8 (the intermediate one in FIG. 1) when coil 2 is energized. The ladder 12 cooperates with armature 6 and is moved downwardly upon energization of coil 2 by engagement of a forwardly extending portion of armature 6 with a surface provided in the lower portion of ladder 12. A pair of restoring springs 13 (only one of which is shown in FIG. I) mounted at the top of the contact stack continuously engage the uppermost shoulders of the movable ladder 12. The springs 13 are pretensioned upwardly to supply a vertical biasing force which restores the armature 6 and the movable ladder 12 to their unoperated or released positions upon the deenergization of the relay coil 2. Further, a fixed ladder 15 forward of the operating ladder 12 is connected to a fixed ladder plate 16, for example by rivets, and is provided with projecting shoulders which securely engage a portion of the tip ends of fixed contact springs 9. The fixed contact springs 9 are pretensioned downwardly for continuously exerting a downward force sufficient to maintain the fixed ladder 15 in a fixed position perpendicular to the core axis.

In reviewing FIG. 1, it is readily noted that a second electromagnetic structure identical to that of relay l and generally characterized by numeral 19, is disposed directly beneath and in parallel alignment therewith. This structure constitutes the electromagnetic unlaching or release unit and comprises an energizing coil 20 mounted on the center leg of an E-shaped rectangular core 21 which is secured at one end to the base of a molded block of insulting material 22. Pivotally mounted to cooperate with the lower surface 23 of the core 21 is a U-shaped armature 24 which extends rearwardly along the outer legs of core 21 on either side of the coil 20 in such a position that the bight of the U will cooperate with the forwardmost end of the core face 23 in the energized condition of coil 20. Like in armature 6, the armature 24 is provided with a tongue or tab portion 25 extending forwardly of the bight or free end of the armature. When the coil 20 is deenergized, the armature 24 assumes a position as shown in FIG. 1. The armature weight alone is sufficient in biasing the armature 24 to a predetermined position as shown in FIG. 1 which is limited by a stop member as will 'be described presently.

The mechanical latching unit generally illustrated by character 30 is suitably positioned adjacent the free ends or bight portions of armatures 6 and 24. More particularly, the mechanical latching unit is disposed in cooperative association with the tongues or tabs 7 and 25 of the armatures 6 and 24, respectively. The mechanical latching unit comprises a mounting bracket 31 provided with two upwardly extending arms 32 carrying a pivot pin 33 which has its axis offset to the right of the tab 7 as shown in FIGS. 2 and 4, the purpose of which will be described hereinafter. A metallic bell-crank or L-shaped lever 34 having a vertically extending arm 35 and a substantially horizontally extending arm 36 is suitable pivotally supported between the arms 32 on the pivot pin 33. The arm 35 includes a curved or hook-like portion formed on its outer extremity for cooperating with the upper surface of tongue 7 for latching the armature 6 of the relay in its operative position, as shown in FIG. 4. In viewing FIG. 4, it is readily noted that the arm 35 includes two straight vertical sections and an intermediate inclined section. It is quite obvious that the vertical height of arm 35 or the distance between the pivot pin 33 and the hook-like portion may be adjusted by simply straightening or bending the intermediate portion thereby changing the angle of inclination. This adjustment not only reduces the tolerance requirements of the overall assembly but also readily allows the proper positioning of the hook-like portion of arm 35 with respect to tab 7. The horizontal arm 36 of lever 34 is adjustably disposed adjacent and above the tongue 25 of armature 24 of the electromagnetic releasing or unlatching unit 19. The lever 34 may be adjusted for proper operation by simply bending arm 36 upwardly or downwardly, as the situation demands. The bracket 31 is provided with an upstanding stop member 37 which cooperates with the lower surface of tab 25 for limiting the downward movement of armature 24 energizing coil 20 is deenergized. The stop member 37 may also be bent inwardly or outwardly as viewed in FIGS. 2 and 4 to provide an air gap adjustment between the core face 23 and armature 24 of the electromagnetic unlatching unit. An elongated holding spring 38 is rigidly secured, for example by rivets, to the apex of the lever 34 for resiliently biasing armature 24 away from the core face 23 and retaining the tab 25 against stop member 37 so that chatter is effectively eliminated when the coil 20 of the unlatching unit is deenergized. An L-shaped leaf spring 39 having one end securely fastened to the base of mounting bracket 31 and the other arm engaging the vertical extending arm 35 of lever 34 constantly urges the arm 35 toward the tongue 7 of armature 6. Accordingly, the spring 39 engages an intermediate portion of arm 35 and yieldingly biases the lever 34 in a counterclockwise direction, as viewed in FIGS. 2 and 4. It is apparent that the degree of tension exerted by spring 39 on lever 34 may be increased and decreased for insuring proper operation by simply varying the angular disposition of the arms of the spring. In order to reduce the amount of frictional wear on elements 7, 25, 35 and 36 without the use of lubricant, it has been found advantageous to polish chrome plate the tongues 7 and 25 and lever 34 to provide smooth operation and increased durability.

The entire relay assembly including the multicontact relay, the electromagnetic unlatching unit and the mechan ical latching unit are suitably secured to a base member 40. An L-shaped insulative support member 41 is securely fastened to the base 40 and carries the rearwardmost ends of the relay and unlatching unit. The insulative block 4 of the electromagnetic relay and the insulative block 22 of the unlatching unit are securely fixed to the upstanding leg 41a of the insulative support member 41 by means of screws 42. The horizontally disposed leg 41b of the insulative support member 41 is suitably positioned between the base member 40 and rearwardmost end of the latching unit to satisfy the necessary high voltage isolating requirements. In actual practice, the relay may be subject to voltages in excess of 3,000 volts, and accordingly the breakdown characteristics of the relay must be capable of withstanding such high voltages. The forwardmost end of the assembly is mounted on an insulating support member 43 which is securely fastened to the base member 40. This forwardmost supporting arrangement includes a plurality of cylindrical spacers 44 through which a pair of screws 45 pass. The bracket 31 is mounted directly on the top surface of the insulative support member 43. A nonmagnetic core plate 46 extending from the forwardmost portion of core 21 is disposed on the lowermost pair of spacers 44. Similarly, a nonmagnetic core plate 47 extending from the forwardmost portion of the core 3 is on the uppermost pair of spacers 44. The bracket 31 and the nonmagnetic core plates 46 and 47 are provided with suitable aligned apertures for accommodating through screws 45 which securely hold the entire supporting structure in proper relationship. This supporting arrangement provides an easy method of assembling and replacing the various elements of the latching relay assembly. For example, the electromagnetic operating relay may be readily removed and replaced by simply removing the associated screw 42 and unloosening the screws 45. Similarly, the electromagnetic unlatching unit may easily be replaced by removing the associated screw 42 and also the screws 45. To replace the mechanically latching unit 30, it is simply necessary to remove the through screws 45. An opaque cover 50, of any suitable material, cooperates with the base plate member 40 and forms a substantially dust-proof and moisture-proof housing for the entire assembly.

First, in describing the operation, it will be assumed that the electromagnetic relay is horizontally disposed and is in its unlatched condition so that the various elements are in the positions shown in FIGS. 1, 2 and 3. Under this condition, the restoring springs 13 hold the armature 6 in its unoperated or released position. That is, the armature 6 is in its uppermost position away from core face 5. Since the coil of the unlatching unit is deenergized, the armature 24 is gravity biased away from the core face 23 and rests against the upper face of the stop member 37, as shown in FIG. 2. The holding spring 38 resiliently urges the tongue against the stop member 37 so that incessant chattering noises do not result from external vibrations, With both the coils 2 and 20 deenergized, the mechanical latching mechanism assumes a position as shown in FIG. 2 wherein the adjacent face of the hook-like portion of arm rests against the side face of tongue 7. It will be noted that the lateral arm 36 of lever 34 is preferably out of contact with the free end of holding spring 38 and in turn the tongue 25 of armature 24. It has been found that this out-of-engagement relationship between the tongue 25 and lateral arm 36 of the lever should always be maintained except when it is desirous t0 unlatch or unlock the electromagnetic relay, as will be described hereinafter. Now let us assume that it is desirous to pick up the electromagnetic relay so that the various controlled circuits may be interrupted and/or completed by the appropriate contact points 10 and 11. Accordingly, upon the energization of the coil 2 the armature 6 overcomes the force exerted thereon by springs 13 and is attracted toward the core 3 which results in a downward movement of the armature 6 and movable ladder 23. As the tongue 7 moves downwardly and its upper surface passes the lower surface of the hook-like portion of arm 35, the spring 39 urges and rotates the lever 34 in a counterclockwise direction causing the armature 6 to be latched in its operated position, as shown in FIG. 4. In viewing FIG. 4, it will be noted that the engaging surface of the hook is so arranged to be flush with the upper surface of tongue 7 so that maximum engagement may be established therebetween. The armature 6 is now positively locked in its operated position and accordingly the coil 2 of the operating relay may be deenergized so that unnecessary energy need not be consumed. It will be noted that the lateral arm 36 of lever 34 is still out of engagement with the free end of holding spring 38 and in turn tongue 25. The purpose of maintaining this outof-contact relationship is to prevent the possibility of external vibrations from causing a possible unlatching of the electromagnetic relay 1. Since vibrations may cause a slight movement of the free armature 24, it is advantageous to allow a certain amount of free play to exist between the lateral arm 36 and the tongue 25. This assures that any slight upward movement of the armature 24 will not be transferred or transmitted to the lever 34 so that the possibility of accidental unlatching is minimized. Further, it has been found in application that the external vibrations exert the greatest force in a downward direction. Accordingly, the disposition of the unlatching unit 19 below the electromagnetic relay 1 and with its armature gravity biased against stop member 37 greatly increases the reliability of the latching relay. For example, the downward vibrational forces simply urge the tongue 25 and armature 24 against the stop member 37. Similarly, the downward vibrational forces cause a counterclockwise movement, as viewed in FIG. 4, to be applied to the lever 34 which increases the latching ability of the hook-like portion of arm 35. That is, the biasing force of spring 39 on arm 35 is supplemented by the moment produced on lever 34 by the downward vibrational forces. Accordingly, increased security in latching is realized.

Now let us assume that it is desirous to unlatch the electromagnetic relay so that the relay armature 6 may return to its released or unoperated position. The relay is unlatched by simply energizing coil 20 of the unlatching unit. The energization of the coil 20 pulls the armature 24 upwardly so that tongue 25 urges spring 38 into into intimate contact with the free end of arm 36 thereby causing clockwise movement to be imparted to the lever 34. The clockwise movement of lever 34 causes the hook like portion of arm 35 to move away from the tongue 7 of the relay armature 6. As previously mentioned, the pivot pin 33 and, therefore, the pivotal point of lever 34 is offset or is disposed to the right of tab 7 so that the lever 34 and in particular hook-like portion of arm 35 moves slightly upwardly during the clockwise movement of lever 34. This away movement of the ho0k-1ike portion of arm 35 not only enhances the unlatching operation but also significantly reduces the functional wear between the engaging surface of the tab and hook-like portion. The releasing of tongue 7 allows the armature 6 and the operating ladder 12 to be returned to their normal unoperated positions. Upon reaching its released position, the coil of the unlatching unit may be deenergized so that its armature will move downwardly against stop 37 and the latching relay again assumes a position as'shown in FIGS. 1, 2 and 3. The relay may again be latched by simply momentarily energizing the coil 2 so that the hook-like portion of the arm 35 again holds the tongue 7 of armature 6, in the manner described above.

It will be observed that the outof-engagement relationship between the tongue of the unlatching armature 24 and the lateral arm 36 of lever 34 substantially eliminates any possibilities of false unlatching due to movement imparted to armature 24 by external vibrations. Also it will be noted that the disposition of the armatures 6 and 24 results in substantially equal and opposite forces to be exerted on the lever 34 due to any extraneous shock. For example, a force exerted by external shock on tab 25 of armature 24 tending to unlatch the armature 6 also exerts a force on armature 6 and in turn, on tab 7 which tends to inhibit the unlatching action.

Further, the parallel disposition or in-line relationship of the lever 34 and armature 24 with the downward vibrational forces enhances the reliability of the latching mechanism and immunizes the latching mechanism against erratic unlatching.

In addition, the integral structure of the mechanical latch and the electromagnetic unlatching unit 19 makes for easy assembling and replacing of these various elements constituting the latching relay.

Further, the highly polished chrome surfaces of the tongues 7 and 25 and the lever 34 greatly decrease the amount of frictional wear and considerably increase the useful lift of the electromagnetic relay and, particularly, of the latching mechanism.

It is quite apparent that it may be desirous to vertically mount the entire assembly in its environmental setting. That is, it may be necessary to dispose the assembly such that base member 40 lies in a vertical plane. Under such a condition the armature 24 is resiliently biased away from the core face 23 by spring 38 without the aid of gravity. It is quite evident that under such a condition the effects of external vibrations and shock are even less severe due to the disposition of the armatures 6 and 27 and the lever 34.

It is understood that while my invention has been described in relation to railroad applications, it is quite obvious that its use is not merely limited thereto but may be employed in other surroundings and environments which have similar operating conditions and require positive latching action.

Further, although I have herein shown and described only one form of a latching mechanism embodying my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

1. In an electromagnetic relay having a core, an operating coil and an armature movable between a first and a second position and cooperatively associated with a contact assembly for opening or closing electrical contacts when the relay is picked up and released comprising: a latching mechanism including a mechanical locking means and an electromagnetic unlocking means, said mechanical locking means including a pivotal lever having one end resiliently biased into cooperative association with the movable armature of the electromagnetic relay for positively locking the movable armature in its second position when the electromagnetic relay is picked up, and said electromagnetic unlocking means including a movable member, and means for biasing said movable member adjacent to but normally out of engagement with the other end of said pivotal lever when said electromagnetic unlocking means is deenergized so that the other end of said pivotal lever is only capable of unlocking and permitting the movable armature of the electromagnetic relay to move to its first position when said electromagnetic unlocking means is energized.

2. An electromagnetic relay of the type described in claim 1, wherein said pivotal lever is in the form of a bell-crank.

3. An electromagnetic relay of the type described in claim 1, wherein said one end of said lever comprises a hook-like portion formed on the outer end thereof for positively locking said movable armature in its second position.

4. An electromagnetic relay of the type described in claim 1, wherein an L-shaped leaf spring resiliently biases said one end of said lever into cooperative association with the movable armature of the electromagnetic relay.

5. An electromagnetic relay of the type described in claim 1, wherein said movable member of said electromagnetic unlocking means is gravity assisted out of engagement with said other end of said lever when said elec tromagnetic unlocking means is deenergized.

6. An electromagnetic relay of the type described in claim 5, wherein a stop member limits the gravitational movement of said movable member when said electromagnetic unlocking means is deenergized.

7. An electromagnetic relay of the type described in claim 6, wherein said biasing means includes an elongated leaf spring which cooperates with said movable member of said unlocking means for biasing said movable member out of engagement with the other end of the pivotal lever and for urging said movable member against said stop member for preventing chattering when said electromagnetic unlocking means is deenergized.

8. A shock-proof latching mechanism for an electromagnetic relay having a contact operating armature comprising: a mechanical latch including a mounting bracket for pivotally supporting a bell-crank, said bell-crank having a hook-like portion formed on one arm thereof, said one arm of said bell-crank formed of straight and inclined sections whereby the length of said one arm of said bell-crank may be varied by changing the angle of inclination of said inclined portion, a spring biasing said one arm of said bell-crank toward the contact operating armature of the electromagnetic relay, an electromagnetic release positioned adjacent the electromagnet relay and having an armature positioned adjacent to the other arm of said bell-crank, means for biasing said armature of said electromagnetic release away from said other 'arm of said bell-crank When said electromagnetic release is deenergized, said hook-like portion of said one arm of said bell-crank latching the contact operating armature in its operated position when the electromagnetic relay is picked up, and said armature of said electromagnetic release moving said other arm of said bell-crank for overcoming the spring bias of said one arm of said bell-crank thereby unlatching the contact operating armature of the electromagnetic relay only when said electromagnetic release is energized.

9. A shock-proof latching mechanism as defined in claim 8, wherein said mounting bracket includes a stop member cooperatively associated with said armature of said electromagnetic release for maintaining a proper armature air gap for said electromagnetic release.

10. A shock-proof latching mechanism as defined in claim 9, wherein said mounting bracket includes a pair of arms for pivotally supporting'said bell-crank about its apex.

11. A shock-proof latching mechanism as defined in claim 8, wherein said arms of said bell-crank form sub-. stantially a degree angle wherein said one arm extends along a substantially vertical plane and said other arm extends along a substantially horizontal plane.

12. A shock-proof latching mechanism as defined in claim 8, wherein said spring comprises an L-shaped leaf spring.

13. A shock-proof latching mechanism as defined in claim 8, wherein the electromagnetic relay and said electromagnetic release are of identical construction and said electromagnetic release is positioned beneath in parallel relationship with the electromagnetic relay.

14. A shock-proof latching mechanism as defined in claim 9, wherein said biasing means includes an elongated leaf spring which resiliently maintains said armature of said electromagnetic release against said stop member.

15. In a shock-proof latching relay: an operating unit comprising an electromagnetic relay having a core, an energizing coil and a contact operating armature movable between an operated and an unoperated position when the energizing coil is energized and deenergized, respectively, a latching unit comprising a mounting bracket, a pivotal lever, a biasing spring and a holding spring disposed adjacent the free end of said contact operating armature, an unlatching unit comprising an electromagnetic device having a core, an energizing coil and a movable armature disposed adjacent said unlatching unit and positioned beneath and in parallel alignment with said electromagnetic relay, said mounting bracket having a pair of upstanding arms and a pivot pin for pivotally supporting said lever, said lever having one end extending upwardly and the other end extending laterally thereof, said upwardly extending end having a hook-like portion formed on its outer extremity which is constantly urged toward said free end of said contact operating armature by said biasing spring, said movable armature of said electromagnetic device having its free end disposed beneath said laterally extending end of said lever and said holding spring, said mounting bracket having an upwardly extending stop for limiting the downward movement of said movable armature of said electromagnetic device, said holding spring normally engaging said free end of said movable armature of said electromagnetic device for preventing chattering thereof, said hook-like portion of said lever effectively engaging and latching said contact operating armature in its operated position when said energizing coil of said electromagnetic relay is energized, and said movable armature of said electromagnetic device effectively engaging the other end of said lever and unlatching said contact operating armature when said energizing coil of said electromagnetic device is energized.

16. A shock-proof latching relay as defined in claim 15, wherein said contacting operating armature of said electromagnetic relay includes a tab portion cooperating with said hook-like portion of said lever, and said movable armature of said electromagnetic device includes a tab portion cooperating with the other end of said lever.

17. A shock-proof latching relay as defined in claim 16, wherein said lever and said tab portions are polished chrome plated for reducing the frictional wear thereof.

References Cited UNITED STATES PATENTS 2,867,756 1/1959 Makowski 335234 2,896,047 7/1959 Breitenstein 335129 3,106,625 10/1963 Marley 335- 3,201,544 8/1965 Diamant 335l20 BERNARD A. GILHEANY, Primary Examiner.

H. BROOME, Assistant Examiner. 

